Case for small explosive device

ABSTRACT

A container for containing an explosive device, including a mitigating layer defining an enclosure openable to insert the explosive device therein and closable to surround the explosive device, the mitigating layer reducing a force of a blast caused by an explosion of the explosive device, and a fragment-retaining layer substantially surrounding the mitigating layer, the fragment-retaining layer being resistant to a remainder of the force of the blast passing through the mitigating layer and retaining fragments propagated by the explosion of the explosive device, such as to reduce potential injury to a person in proximity of the container.

RELATED APPLICATION(S)

This application claims priority on U.S. provisional application Ser.No. 60/713,740 filed Sep. 6, 2005, the entire specification of which isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to explosion containment, and moreparticularly to a container allowing safe transport of at least onesmall explosive device.

BACKGROUND ART

Millions of small explosive devices such as detonators, detonating cord,airbag inflators and fuses are made and shipped every year. Detonators,detonating cord, uncased explosives, and other devices containing smallexplosive charges are widely used by many security and militaryagencies, for example for the destruction of suspect explosive devices,disposal of unexploded munitions, and wall breaching during hostagerescue operations. These devices are also widely used in the petroleumindustry, the entertainment industry, the construction industry, etc.

As a result, small explosive devices and charges often need to becarried in the presence of others, including the general public, usuallyin portable cases, such as when detonators and detonating cords aretaken by security personnel to sites where operations require breachingwalls and destruction of explosive materials.

Upon detonation, rapid combustion processes produced even by a smallexplosive device compress surrounding fluid media so quickly that shockwaves are produced. Also, the physical expansion of the hot blastcombustion products adds to pressure loading of objects in its path, aswell as generates radiation. The hot blast combustion products aretypically capable of igniting combustible materials nearby andinflicting burns on exposed humans. Humans may be killed by intenseblast pressure alone, as this causes lung damage above threshold levels.Below threshold conditions for fatal injury, blast pressure may causedamage to ears and lungs, and sudden accelerations that lead to spinalinjuries. Moreover, fragments from exploding cased explosive devices maylead to fatal internal damage.

Explosive effects dissipate rapidly in air as long as the blast isunconfined. Large obstructions such as buildings surrounding a street inwhich a blast occurs prolong pressure durations and lead to greaterdamaging capability. Complete or near-total confinement maximizes blasteffect duration, as the blast pressure is prevented from beingdissipated.

In order to provide safe handling of small explosive devices, it isoften desired to prevent detonation of one explosive charge from causingdetonation of others nearby, an event widely termed “sympatheticdetonation”, as mass detonation of large quantities of small explosivecharges generates blast parameters equivalent to single-chargedetonations of similar weight. A number of prior art small explosivedevices containers are designed to prevent sympathetic detonation, butnot to confine either blast effect or fragments. As a result, suchcontainers are usually destroyed when the elements contained thereinexplodes, and components are hurled at significant velocities. As such,these containers would be unsuitable for transportation of smallexplosive devices next to people, as the components projected by theexplosion could cause serious injury.

For example, in U.S. Pat. No. 5,160,468, Halsey et al. disclose the useof a mitigating material, pumice, to surround hard plastic tubes tocontain explosive devices. The hard plastic tube forms a barrier betweenthe explosion and the mitigating material. If the plastic tube isomitted, the mitigating material attenuates the blast pressure but isnot adapted to retain fragments produced by the blast.

Accordingly, there is a need for an improved container allowing safetransportation of small explosive devices.

SUMMARY OF INVENTION

It is therefore an aim of the present invention to provide an improvedcontainer allowing safe transportation of small explosive devices.

Therefore, in accordance with the present invention, there is provided acontainer for containing an explosive device, the container comprising amitigating layer defining an enclosure openable to insert the explosivedevice therein and closable to surround the explosive device, themitigating layer reducing a force of a blast caused by an explosion ofthe explosive device, and a fragment-retaining layer substantiallysurrounding the mitigating layer, the fragment-retaining layer beingresistant to a remainder of the force of the blast passing through themitigating layer and retaining fragments propagated by the explosion ofthe explosive device, such as to reduce potential injury to a person inproximity of the container.

Also in accordance with the present invention, there is provided acontainer for containing an explosive device, the container comprisingan outer shell including a body and a cover relatively movable betweenan open position and a closed position, a fragment-retaining layerdisposed against inner surfaces of the body and the cover such as tosubstantially define a first enclosure when the body and the cover arein the closed position, a mitigating layer disposed against innersurfaces of the fragment-retaining layer such as to define a secondenclosure within the first enclosure when the body and cover are in theclosed position, the second enclosure being adapted to receive theexplosive device therein, wherein the mitigating layer reduces a forceof a blast caused by an explosion of the explosive device, and thefragment-retaining layer resists a remainder of the force of the blastpassing through the mitigating layer and retains fragments propagated bythe explosion.

Further in accordance with the present invention, there is provided amethod of containing an explosion of an explosive device, the methodcomprising reducing a force of the explosion using a mitigating layersurrounding the explosive device, and containing the reduced force ofthe explosion and fragments projected by the explosion using afragment-retaining layer surrounding the mitigating layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the accompanying drawings, showing by wayof illustration a preferred embodiment of the present invention and inwhich:

FIG. 1 is a perspective view of a container according to a preferredembodiment of the present invention; and

FIG. 2 is a cross-sectional view of the container of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, a container or transport case 10according to the present invention is shown. The case 10 comprises anouter shell 12 surrounding a fragment-retaining layer 14, whichsurrounds a mitigating layer 16.

The outer shell 12 preferably has a rectangular cross-section, andincludes a body 18 and a cover 20 which together define an enclosure,also preferably of rectangular cross-section. In a particularembodiment, the outer shell 12 protects the internal components andmaterials being transported from weather and incidental damage, and assuch is made of a shock resistant plastic, for example a polypropylenecopolymer such as Coroplast™. Alternate materials for the outer shellinclude wood or any appropriate type of metal such as for example steelor aluminum.

In the embodiment shown, the cover 20 is pivotally retained on the body18 through hinges 22. The body 18 and cover 20 also include lockingmeans 24 retaining the cover 20 in the closed position when engaged.Alternatively, the hinged cover 20 can be replaced by a cover completelyseparate from the body 18, or by a guillotine-type door, a hatch-typedoor, a drawer, a plurality of doors, etc.

In a particular embodiment, the case 10 is designed to handle smallexplosive devices (e.g. less than 1 kg total of TNT-equivalentexplosive), and as such the hinges 22 and locking means 24 allow somegas to escape between the closed cover 20 and the body 18, with the gasleakage and attendant shock waves mitigated to the extent required toprevent permanent injury to nearby people or prevent sympatheticdetonation or burning of nearby energetic materials. In an alternateembodiment, the case 10 is used to contain explosive devices and otherdevices that may contain hazardous biological, radioactive, or chemicalagents that could be dispersed under pressure, and as such the sealbetween the cover 20 and body 18 is adequate to prevent release of thehazardous material. The degree to which the seal is impervious to thetransmission of gas can thus be varied through various closuremodifications readily available to one in the art.

A handle 26, which may be fixed or extendable, is attached to the body18 to facilitate transport of the case 10 either by hand or by a roboticdevice. It is also considered to provide the case 10 with more than onehandle 26, or alternatively with no handle at all.

The fragment-retaining layer 14 is located within the enclosure definedby the outer shell 12 and is in contact therewith. Thefragment-retaining layer 14 includes a bottom sheet 28 and four (4) sidesheets 30 located in the body 18, and a top sheet 32 located in thecover 20. The bottom and side sheets 28, 30 preferably abut one anotherand the sheets 28, 30, 32 together define an enclosure within theenclosure of the outer shell 12.

The sheets 28, 30, 32 of the fragment-retaining layer 14 are made of afragment-retaining material which minimize shock wave transmission aswell as retains fragments propagated by an explosion of a sizecorresponding to the explosive device(s) to be transported in the case10. In a particular embodiment, the sheets 28, 30, 32 are made ofpolycarbonate, such as Lexan®, as this material has been proven todeform plastically to a great extent under explosive loading withoutrupture. Polycarbonate also features low acoustic impedance, which isdesirable for shock wave attenuation. Alternatively, the sheets 28, 30,32 can be made of a metal of similar properties and/or can compriseballistic armor in order to protect the encased explosive devices fromimpinging projectiles or ammunition fragments. As such, thefragment-retaining layer 14 resists to a remainder of the blast forcepassing through the mitigating layer 16.

The mitigating layer 16 is located within the enclosure defined by thefragment-retaining layer 14 and is in contact therewith. A bottom panel34 is located against the bottom sheet 28, a side panel 36 is locatedagainst each of the side sheets 30, and a top panel 38 is locatedagainst the top sheet 32. The inner surfaces 56 of the panels 34, 36, 38define an enclosure for the explosive device which will be contained inthe case 10.

The panels 34, 36, 38 of the mitigating layer 16 are formed of a blasteffect mitigating material which effectively reduces the strength of theblast of an explosive device in close proximity. Examples of suchmaterials are disclosed by Gettle et al. in U.S. Pat. Nos. 5,225,622 and5,394,786, which are both incorporated herein by reference. Themitigation mechanism of such materials is a combination of mechanicaland chemical factors that stop the chemical reaction of the explosivebefore the entire explosive is consumed. A portion of the remainder ofthe explosive force is mitigated as it passes through the material. In apreferred embodiment, the panels 34, 36, 38 are made from lightweighthoneycomb filled with attenuating filler material and sealed off on bothsides with a thin relatively friable tissue. Other mitigating materialscan also be used in the panels 34, 36, 38, such as pumice, foamedplastic beads, etc.

Although the mitigating layer 16 is shown as being formed of separatepanels, it can also be integrally cast or otherwise molded to maintainan intended shape. Alternatively, the mitigating layer 16 can be tubularor in the form of amorphous bags of blast effect mitigating material solong as the bags are adequately secured to resist displacement whenmoved or disturbed.

The inner surfaces 56 of the panels 34, 36, 38, which define theenclosure where the explosive device will be contained, includes aninterior lining that either provides negligible resistance to or delayin rupture, or permits transmission of the impinging blast wave into theblast effect mitigating material. In a preferred embodiment, the liningis perforated or otherwise permanently open to the unobstructed flow ofgas between the space where explosive devices and materials are placedand the blast effect mitigating material.

Alternatively, the lining can be a fabric or metal foil that preventspenetration of moisture or spilled fluids into the blast effectmitigating material, a frangible material resistant to the transmissionof gas in ambient conditions but otherwise readily ruptured by theimpingement of a blast in the event of a detonation inside the case 10.Such a lining would be preferable when the blast effect mitigatingmaterial is a gel or fluid, or when powdered, liquid, or gaseousextinguishing agents are employed that assist in mitigating explosiveeffects or otherwise serve to suppress post-blast ignition of nearbyflammable materials.

In the embodiment shown, the case 10 includes at least one blast effectmitigating divider 40, such that opposed exposed surfaces 58 of thedivider 40 define together with the inner surfaces 56 of the panels 34,36, 38 a plurality of separate compartments, in order to resist orinhibit the occurrence of sympathetic detonation when more sensitiveexplosive devices are carried. In FIG. 1, two such dividers 40 areillustrated, extending throughout the enclosure defined by themitigating layer 16 in a perpendicular manner.

Each divider 40 includes a middle sheet 42 sandwiched between twodivider panels 44. The middle sheet 42, like the bottom, side and topsheets 28, 30, 32 of the fragment-retaining layer 14, is composed of afragment-retaining material such as for example polycarbonate. Like thesheets 28, 30, 32, the middle sheet 42 can also include ballistic armorto prevent fragments and projectiles such as bullets from impactingexplosive devices inside the compartment. The divider panels 44 arecomposed of blast effect mitigation material similarly to the bottom,side and top panels 34, 36, 38 of the mitigating layer 16. The opposedexposed surfaces 58 of the divider panels 44 include an interior liningsimilar to the lining of the inner surfaces 56 of the panels 34, 36, 38.

In the embodiment shown, the case 10 also includes removable blasteffect mitigating dividers 46, one of which is shown in FIG. 1. Theremovable dividers 46 each include a middle sheet 48 similar to themiddle sheet 42 of the divider 40, sandwiched between two divider panels50 similar to the divider panels 44 of the divider 40. The removabledividers 46 also includes opposed exposed surfaces 60 including a liningsimilar to the lining of the exposed surfaces 58 of the divider 40. Theremovable dividers 46 are sized such as to be snuggly slidable within acompartment of the enclosure defined by the mitigating layer 16.

In a particular embodiment, the dividers 40 and removable dividers 46are intended to prevent sympathetic detonation between explosive deviceslocated in separate compartments. However, prevention of sympatheticdetonation is not essential. The critical requirement is that in theevent of a detonation of one or more explosive devices within the case10, release of blast generated gas, from the case 10, is so slight thatno permanent injury is inflicted on humans in close proximity to thecase 10. Fragments from explosive device components, and components ofthe case 10, are preferably completely confined. Extremely rapid coolingof hot gaseous products is also preferable such as to prevent possibleignition of case materials and other items kept within the case 10.

Alternatively, it is considered to provide a case 10 without thedividers 40 and/or without the removable dividers 46. For example, thecase 10 can provide a single compartment.

In the embodiment shown, the body 18 includes an inspection port 54,formed by aligned holes through the outer shell 12, fragment-retaininglayer 14 and mitigating layer 16. The port 54 facilitates examination orcharacterization by various means so that inspection devices such asoptical and other electromagnetic imaging devices, chemical sensors, andradiation detection probes may be installed in appropriate locations.Alternatively, the port 54 may be provided with an appropriate nozzle toinject various kinds of agents, such as aqueous foams for blast effectmitigation or neutralizing of chemical or biological agents, or cleaningmaterial for scrubbing radioactive dusts. The port 54, when not in use,is closed by an appropriate cover (not shown). Alternately, the port 54can be omitted.

In the embodiment shown, the body 18 also includes at least one vent 52,which is defined by an aperture cut in one wall of the outer shell 12,in order to release hot blast gases. Preferably, the vent 52 is locatednear explosive devices within the case 10 and is vented in a directionaway from a person carrying the case 10. The vent 52 is covered by theportion of the wall of the outer shell 12 removed to form the aperture(not shown), re-attached over the aperture in such a manner that thevent cover is easily dislodged under internal pressure.

Alternately, the vent 52 could be located in other locations, forexample in corners of the outer shell 12. Also, alternate covers for thevent 52 include an elastic or flexible bag that expands underpressurization caused by an internal explosion. This expandable membermay be substantially comprised of a fabric or plurality of fabric layerscapable of catching debris and fragments from the detonation of a storedexplosive device. Alternatively, the expandable member may besubstantially comprised of a mesh that allows gradual release ofinternal gas, thereby reducing the loads imparted by the blast to thehinges 22 and locking means 24. Any combination of such components forvent covers can be made by an individual skilled in the design of blastprotection devices, such as bellows-type components combined with meshand elastic “balloon” components.

Although not shown, mountings or other provisions for cylindricalvessels, or other shapes of explosive devices, may be provided in thecompartments. Straps or other similar components can be provided foradditional restraint to the explosive devices within the compartments.

In a particular embodiment, wheels (not shown) are attached to the outershell 12 to facilitate movement of the case 10 by hand or robot. Thewheels may be integral to the outer shell 12, or be provided bydetachable means enabling the wheel assembly to be removed when notneeded. Alternatively, skids may be provided that also serve tofacilitate movement.

Moreover, explosive devices or other items may be placed in protectivecartons or wraps within the compartments to provide additional levels ofprotection. Such wraps and cartons may be substantially comprised ofhigh-strength materials that resist bullets and ammunition fragmentsfrom penetrating.

The case 10 (as well as detachable wheels, if provided) may be providedwith a bag enclosure that seals the case 10 when it is shut, to preventrelease of dangerous materials to the external environment, for instanceif the device within contains radioactive materials or potentiallylethal pathogens. The bag enclosure may be part of the detachablewheeled or skid device, attached to the outer shell 12, or incorporatedwith the internal compartments or linings of the case 10. This bagenclosure may be coated or otherwise substantially comprised ofmaterials that serve to neutralize the anticipated hazard.

The case 10 can also include shielding against the transmission ofelectromagnetic radiation or interference (EMI), including the effectsof electromagnetic pulse (generally designated as EMP) when the case 10is closed. The case 10, acting as a protection system, thus protectsexplosive devices kept therewithin from unintentional detonation orneutralization from radio waves or other electromagnetic events presentoutside the closed case 10. Provisions for electrical grounding may alsobe placed in suitable locations of the case 10 in order to prevent thebuildup of static electricity.

Part or all of the outer shell 12 may utilize materials that facilitateexternal examination of the case contents, such as those permittingtransmission therethrough of a desired portion of the electromagneticspectrum. The fragment-retaining layer 14 and the mitigating layer 16may be made of materials that are correspondingly similar.

The outer surface of the outer shell 12, the inner surfaces 56, and theexposed surfaces 58, 60, either alone or in combination, may be coatedwith fire-resistant materials in order to avoid ignition upon detonationof an encased explosive device. This is preferable when the case 10 isdestined to contain energetic materials that may be capable of sustainedburning with or without access to ambient air.

Should vessels or containers storing radioactive, chemical, orbiological agents be placed within cases where explosive devices arealso kept, internal protective components that prevent piercing theagent container may be integrated within the second enclosure.

The case 10 of the present invention thus minimizes the release ofpotentially hazardous phenomena under pressure above ambient to theenvironment external to it. Thus shock waves and pressurized gas leakageare mitigated to the degree desired by those who may be come into closeproximity to the case 10 when explosive devices are containedtherewithin.

The mitigating layer 16 preferably provides substantial cushioning inorder to protect explosive devices placed within the case 10 from shockand impact. Thus, the case 10 may be dropped, fall from a movingvehicle, stepped on, crushed by stacking with heavy objects, or struckby bullets with a reduced risk of explosion of the contained explosivedevices or, in the case of an explosion, with limited risk of injury topeople nearby. As it often is required to be carried by hand, the case10 is preferably sized such as to be relatively light.

The case 10, sized accordingly, can safely contain a variety of smallexplosive devices, including, but not limited to, detonators, detonatingcords, airbag inflators, fuses, small hand grenades, smallanti-personnel mines, various recovered explosive devices, etc.

Although the case 10 has been described as a portable case, it is alsoconsidered to integrate the case in a rolling cart, in a vehicle, in abuilding, etc. Where the case 10 is integrated in an enclosure of anexisting structure, the outer shell 12 can be omitted. The caseintegrated in a rolling cart could be used, for example, in an airplane,where the rolling cart would be of a serving-cart type, to be rolled inproximity of a potentially dangerous device found, so that the devicecould be place within the case 10 with minimal handling. The caseintegrated in a vehicle could be used, for example, in a the cabin of alaw enforcement vehicle, to transport small explosive devices destinedto explode suspect devices, or to transport the suspect devicesthemselves away from the public.

The embodiments of the invention described above are intended to beexemplary. Those skilled in the art will therefore appreciate that theforegoing description is illustrative only, and that various otheralternatives and modifications can be devised without departing from thespirit of the present invention. Accordingly, the present invention isintended to embrace all such alternatives, modifications and varianceswhich fall within the scope of the appended claims.

1. A container for containing an explosive device, the containercomprising: a mitigating layer defining an enclosure openable to insertthe explosive device therein and closable to surround the explosivedevice, the mitigating layer reducing a force of a blast caused by anexplosion of the explosive device; and a fragment-retaining layersubstantially surrounding the mitigating layer, the fragment-retaininglayer being resistant to a remainder of the force of the blast passingthrough the mitigating layer and retaining fragments propagated by theexplosion of the explosive device, such as to reduce potential injury toa person in proximity of the container.
 2. The container as defined inclaim 1, wherein the fragment-retaining layer retains all fragmentspropagated by the explosion of the explosive device.
 3. The container asdefined in claim 1, further comprising an outer shell surrounding thefragment-retaining layer, the outer shell having a body and a cover,part of the fragment-retaining layer and mitigating layer being locatedwithin the body and a remainder of the fragment-retaining layer andmitigating layer being located within the cover, the body and coverbeing relatively movable between an open position to open the enclosureand a closed position to close the enclosure.
 4. The container asdefined in claim 3, wherein the outer shell is made of shock resistantplastic.
 5. The container as defined in claim 3, wherein the outer shellincludes a vent for high pressure gas created by the explosion of theexplosive device.
 6. The container as defined in claim 5, wherein thevent includes an aperture defined through the outer shell and closed bya cover which is one of dislodged and expanded by the high pressure gas.7. The container as defined in claim 3, wherein the outer shell includesshielding preventing a transmission of electromagnetic radiation orinterference therethrough.
 8. The container as defined in claim 1,wherein the blast effect mitigation material includes a honeycombstructure extending between two plies of friable tissue, the honeycombstructure being filled with attenuating filler material.
 9. Thecontainer as defined in claim 1, wherein the fragment-retaining layerincludes at least one of ballistic armor and polycarbonate.
 10. Thecontainer as defined in claim 1, further comprising at least one blasteffect mitigating divider extending across the enclosure and defining atleast first and second compartments on either side thereof, each of thecompartments being adapted to receive one of the explosive device and atleast one additional explosive device therein, the divider reducing arisk of sympathetic detonation between the explosive devices.
 11. Thecontainer as defined in claim 9, wherein the divider includes a middlesheet for retaining fragments propagated by the explosion of any one ofthe explosive devices, the middle sheet being sandwiched between twopanels of material reducing the force of the blast caused by theexplosion.
 12. The container as defined in claim 1, wherein thefragment-retaining layer has a first hole defined therethrough and themitigating layer has a second hole defined therethrough in alignmentwith the first hole, at least one of the first and second holes beingselectively opened and closed such as to define a port allowing at leastone of insertion of an inspection device and injection of an agent intothe enclosure.
 13. The container as defined in claim 1, wherein at leastpart of the fragment-retaining layer and the mitigating layer permitstransmission therethrough of a desired portion of the electromagneticspectrum.
 14. The container as defined in claim 1, wherein innersurfaces of the mitigating layer are coated with a fire-resistantmaterial.
 15. A container for containing an explosive device, thecontainer comprising: an outer shell including a body and a coverrelatively movable between an open position and a closed position; afragment-retaining layer disposed against inner surfaces of the body andthe cover such as to substantially define a first enclosure when thebody and the cover are in the closed position; a mitigating layerdisposed against inner surfaces of the fragment-retaining layer such asto define a second enclosure within the first enclosure when the bodyand cover are in the closed position, the second enclosure being adaptedto receive the explosive device therein; wherein the mitigating layerreduces a force of a blast caused by an explosion of the explosivedevice, and the fragment-retaining layer resists a remainder of theforce of the blast passing through the mitigating layer and retainsfragments propagated by the explosion.
 16. The container as defined inclaim 15, further comprising at least one blast effect mitigatingdivider extending across the second enclosure and defining at leastfirst and second compartments on either side thereof, each of thecompartments being adapted to receive one of the explosive device and atleast one additional explosive device therein, the divider reducing arisk of sympathetic detonation between the explosive devices.
 17. Thecontainer as defined in claim 16, wherein the divider is removable. 18.The container as defined in claim 16, wherein the divider includes amiddle sheet made of the same material as that of the fragment-retaininglayer, the middle sheet being sandwiched between two panels of the samematerial as that of the mitigating layer.
 19. A method of containing anexplosion of an explosive device, the method comprising: reducing aforce of the explosion using a mitigating layer surrounding theexplosive device; and containing the reduced force of the explosion andfragments projected by the explosion using a fragment-retaining layersurrounding the mitigating layer.
 20. The method as defined in claim 19,further comprising minimizing transmission of a shock wave produced bythe explosion using the fragment-retaining layer.